* [PATCH v2 1/2] dmaengine: Cleanups for the slave <-> channel symlink support
2020-01-31 9:38 [PATCH v2 0/2] dmaengine: Cleanups for symlink handling and debugfs support Peter Ujfalusi
@ 2020-01-31 9:38 ` Peter Ujfalusi
2020-02-03 4:19 ` Vinod Koul
2020-01-31 9:38 ` [PATCH v2 2/2] dmaengine: Add basic debugfs support Peter Ujfalusi
1 sibling, 1 reply; 4+ messages in thread
From: Peter Ujfalusi @ 2020-01-31 9:38 UTC (permalink / raw)
To: vkoul; +Cc: dmaengine, linux-kernel, dan.j.williams, geert
No need to use goto to jump over the
return chan ? chan : ERR_PTR(-EPROBE_DEFER);
We can just revert the check and return right there.
Do not fail the channel request if the chan->name allocation fails, but
print a warning about it.
Change the dev_err to dev_warn if sysfs_create_link() fails as it is not
fatal.
Only attempt to remove the DMA_SLAVE_NAME symlink if it is created - or it
was attempted to be created.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
drivers/dma/dmaengine.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 7b1cefc3213a..342d23132fca 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -756,22 +756,21 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name)
}
mutex_unlock(&dma_list_mutex);
- if (!IS_ERR_OR_NULL(chan))
- goto found;
-
- return chan ? chan : ERR_PTR(-EPROBE_DEFER);
+ if (IS_ERR_OR_NULL(chan))
+ return chan ? chan : ERR_PTR(-EPROBE_DEFER);
found:
- chan->slave = dev;
chan->name = kasprintf(GFP_KERNEL, "dma:%s", name);
if (!chan->name)
- return ERR_PTR(-ENOMEM);
+ return chan;
+ chan->slave = dev;
if (sysfs_create_link(&chan->dev->device.kobj, &dev->kobj,
DMA_SLAVE_NAME))
- dev_err(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
+ dev_warn(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
if (sysfs_create_link(&dev->kobj, &chan->dev->device.kobj, chan->name))
- dev_err(dev, "Cannot create DMA %s symlink\n", chan->name);
+ dev_warn(dev, "Cannot create DMA %s symlink\n", chan->name);
+
return chan;
}
EXPORT_SYMBOL_GPL(dma_request_chan);
@@ -830,13 +829,14 @@ void dma_release_channel(struct dma_chan *chan)
/* drop PRIVATE cap enabled by __dma_request_channel() */
if (--chan->device->privatecnt == 0)
dma_cap_clear(DMA_PRIVATE, chan->device->cap_mask);
+
if (chan->slave) {
+ sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
sysfs_remove_link(&chan->slave->kobj, chan->name);
kfree(chan->name);
chan->name = NULL;
chan->slave = NULL;
}
- sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL_GPL(dma_release_channel);
--
Peter
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2 2/2] dmaengine: Add basic debugfs support
2020-01-31 9:38 [PATCH v2 0/2] dmaengine: Cleanups for symlink handling and debugfs support Peter Ujfalusi
2020-01-31 9:38 ` [PATCH v2 1/2] dmaengine: Cleanups for the slave <-> channel symlink support Peter Ujfalusi
@ 2020-01-31 9:38 ` Peter Ujfalusi
1 sibling, 0 replies; 4+ messages in thread
From: Peter Ujfalusi @ 2020-01-31 9:38 UTC (permalink / raw)
To: vkoul; +Cc: dmaengine, linux-kernel, dan.j.williams, geert
Via the /sys/kernel/debug/dmaengine users can get information about the
DMA devices and the used channels.
Example output on am654-evm with audio using two channels and after running
dmatest on 6 channels:
# cat /sys/kernel/debug/dmaengine
dma0 (285c0000.dma-controller): number of channels: 96
dma1 (31150000.dma-controller): number of channels: 267
dma1chan0: 2b00000.mcasp:tx
dma1chan1: 2b00000.mcasp:rx
dma1chan2: in-use
dma1chan3: in-use
dma1chan4: in-use
dma1chan5: in-use
dma1chan6: in-use
dma1chan7: in-use
For slave channels we can show the device and the channel name a given
channel is requested.
For non slave devices the only information we know is that the channel is
in use.
DMA drivers can implement the optional dbg_show callback to provide
controller specific information instead of the generic one.
It is easy to extend the generic dmaengine_dbg_show() to print additional
information about the used channels.
I have taken the idea from gpiolib.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
drivers/dma/dmaengine.c | 66 +++++++++++++++++++++++++++++++++++++++
include/linux/dmaengine.h | 12 ++++++-
2 files changed, 77 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 342d23132fca..121231300d35 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -32,6 +32,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/platform_device.h>
+#include <linux/debugfs.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/module.h>
@@ -760,6 +761,11 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name)
return chan ? chan : ERR_PTR(-EPROBE_DEFER);
found:
+#ifdef CONFIG_DEBUG_FS
+ chan->dbg_client_name = kasprintf(GFP_KERNEL, "%s:%s", dev_name(dev),
+ name);
+#endif
+
chan->name = kasprintf(GFP_KERNEL, "dma:%s", name);
if (!chan->name)
return chan;
@@ -837,6 +843,11 @@ void dma_release_channel(struct dma_chan *chan)
chan->name = NULL;
chan->slave = NULL;
}
+
+#ifdef CONFIG_DEBUG_FS
+ kfree(chan->dbg_client_name);
+ chan->dbg_client_name = NULL;
+#endif
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL_GPL(dma_release_channel);
@@ -1559,3 +1570,58 @@ static int __init dma_bus_init(void)
return class_register(&dma_devclass);
}
arch_initcall(dma_bus_init);
+
+#ifdef CONFIG_DEBUG_FS
+static void dmaengine_dbg_show(struct seq_file *s, struct dma_device *dma_dev)
+{
+ struct dma_chan *chan;
+
+ list_for_each_entry(chan, &dma_dev->channels, device_node) {
+ if (chan->client_count) {
+ seq_printf(s, " dma%dchan%-4d| %s",
+ dma_dev->dev_id, chan->chan_id,
+ chan->dbg_client_name ?: "in-use");
+
+ if (chan->router)
+ seq_printf(s, " (via router: %s)\n",
+ dev_name(chan->router->dev));
+ else
+ seq_puts(s, "\n");
+ }
+ }
+}
+
+static int dmaengine_debugfs_show(struct seq_file *s, void *data)
+{
+ struct dma_device *dma_dev = NULL;
+
+ mutex_lock(&dma_list_mutex);
+ list_for_each_entry(dma_dev, &dma_device_list, global_node) {
+ seq_printf(s, "dma%d (%s): number of channels: %u\n",
+ dma_dev->dev_id, dev_name(dma_dev->dev),
+ dma_dev->chancnt);
+
+ if (dma_dev->dbg_show)
+ dma_dev->dbg_show(s, dma_dev);
+ else
+ dmaengine_dbg_show(s, dma_dev);
+
+ if (!list_is_last(&dma_dev->global_node, &dma_device_list))
+ seq_puts(s, "\n");
+ }
+ mutex_unlock(&dma_list_mutex);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(dmaengine_debugfs);
+
+static int __init dmaengine_debugfs_init(void)
+{
+ /* /sys/kernel/debug/dmaengine */
+ debugfs_create_file("dmaengine", 0444, NULL, NULL,
+ &dmaengine_debugfs_fops);
+ return 0;
+}
+late_initcall(dmaengine_debugfs_init);
+
+#endif /* DEBUG_FS */
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 64461fc64e1b..9f232b7618f1 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -300,6 +300,8 @@ struct dma_router {
* @chan_id: channel ID for sysfs
* @dev: class device for sysfs
* @name: backlink name for sysfs
+ * @dbg_client_name: slave name for debugfs in format:
+ * dev_name(requester's dev):channel name, for example: "2b00000.mcasp:tx"
* @device_node: used to add this to the device chan list
* @local: per-cpu pointer to a struct dma_chan_percpu
* @client_count: how many clients are using this channel
@@ -318,6 +320,9 @@ struct dma_chan {
int chan_id;
struct dma_chan_dev *dev;
const char *name;
+#ifdef CONFIG_DEBUG_FS
+ char *dbg_client_name;
+#endif
struct list_head device_node;
struct dma_chan_percpu __percpu *local;
@@ -805,7 +810,9 @@ struct dma_filter {
* called and there are no further references to this structure. This
* must be implemented to free resources however many existing drivers
* do not and are therefore not safe to unbind while in use.
- *
+ * @dbg_show: optional routine to show contents in debugfs; default code
+ * will be used when this is omitted, but custom code can show extra,
+ * controller specific information.
*/
struct dma_device {
struct kref ref;
@@ -891,6 +898,9 @@ struct dma_device {
struct dma_tx_state *txstate);
void (*device_issue_pending)(struct dma_chan *chan);
void (*device_release)(struct dma_device *dev);
+#ifdef CONFIG_DEBUG_FS
+ void (*dbg_show)(struct seq_file *s, struct dma_device *dev);
+#endif
};
static inline int dmaengine_slave_config(struct dma_chan *chan,
--
Peter
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
^ permalink raw reply related [flat|nested] 4+ messages in thread